


Train Ride

by lambkind



Category: Undertale (Video Game)
Genre: Established Relationship, Gender-neutral Reader, Other, Public Masturbation, Public Sex, Reader Doesn't Get Off, Sensitive bones, Sex Toys Under Clothing, Sub Sans
Language: English
Status: Completed
Published: 2017-03-03
Updated: 2017-03-03
Packaged: 2018-09-28 01:21:53
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 1,822
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/10061567
Author URL: https://archiveofourown.org/users/lambkind/pseuds/lambkind
Summary: Two hours to Boston, what else are you supposed to do? ¯\_(ツ)_/¯





	

**Author's Note:**

> [Birdteeth](http://archiveofourown.org/users/Birdteeth/pseuds/Birdteeth) gave me the idea for this. Every day I drift further from god's light.

It’s a beautiful day outside. Stretches of bright green woodlands fly by out the window, with splashes of yellow where the ash trees are just starting to turn for the Fall. The train is not loud, but it’s not quiet either. Aside from the muffled conversation of your fellow passengers, most of what you hear is the ambient hum and clatter of the train itself, and Sans’s labored breathing from the seat beside you. If you lean into him and listen carefully, you can just barely make out the low whir of the vibrator under the rumble of the train.

It’s taped to his pelvis under his shorts, just over the pubic symphysis; one of those little bullet-shaped numbers wired to a remote. You laugh thinking about the hours’ worth of research you put into the purchase, specifically looking for the weakest motor you could find. In the end Sans picked it out himself. He said it was almost the same color as your soul, which was actually a pretty romantic gesture, considering that he’d known exactly where and how you planned to use it.

“can’t wait to get kicked off the train!” he said as you boarded, laughing and throwing you a rakish look.

He’s not laughing now though. He’s tense, trying not to fidget, eyes narrowed and over-bright. Your joined hands rest against his knee, which trembles slightly, and his fingers dig into the back of your hand.

“Doing ok?” you ask in a low voice.

He heaves a shaky sigh. “‘m losin’ my fuckin’ mind…”

“Hang in there, buddy,” you say, in imitation of his normally dry tone. The vibrator is set to the lowest setting—not enough to get off on, not loud enough for anyone around to hear, but enough to have become a constant low torment as it gently stimulates the sensitive bone. You see his other hand twitch toward the waistband of his shorts, before curling into a tight fist on the seat next to him. It excites you to imagine how he must be feeling, weak with need and the effort of keeping quiet. How long has it been already? Twenty minutes? Thirty? You’d worried that it might just make him sore after a while, but he hasn’t asked you to stop yet. In fact, he does the opposite.

His voice drops into a hoarse whisper. “please,” he begs. “please turn it up.”

“Nuh uh,” you say playfully. He groans in quiet frustration and lets his eyes fall shut. The rule is, he’s not allowed to touch himself or the vibrator. Only you can do that. If you feel like it.

You pry your hand out of his and put your arm around his shoulders, drawing him closer to you. His hand immediately finds your thigh so his fingers can dig in there instead. He’s not allowed to touch you any more than that.

You press a kiss to his temple, then whisper against his skull, “If we turn it up people will be able to hear.” Actually you’re not sure if that’s true; the noise of the train would probably still drown it out. Sans probably  _ knows _ it’s not true, but if he does, he doesn’t say anything, choosing to play along instead.

Grinning, you slide your hand down his back, feeling the jagged outline of his spine through his jacket, then slip your hand down the back of his shorts. His breath hitches as you run your palm along the top of his hipbone, and his fingers tighten on your leg, guaranteeing a ring of little bruises by tomorrow. Anticipation and prolonged arousal have made him unusually sensitive. When you slide your fingers onto his sacrum he practically flinches, and his teeth clamp shut on a hoarse cry that he fails to contain completely.

“Shhhh,” you say, soothingly, massaging the bone in little slow circles.

“god, yes—” he cuts out, on a ragged breath. “please touch me please—”

He squirms in his seat, trying to push himself into your fingers, wordlessly begging for more friction. You try to keep your touch light but he’s so worked up and desperate that even this might be enough to get him off. Before it can go any farther you withdraw your fingers, reaching up to hook them over a few of his ribs instead, steadying him. He looks almost comically upset by the loss of sensation.

“fuck...” he breathes, falling back against you, but beyond that he offers no complaint. Trying to be good. Laughing a little under your breath, you kiss his flushed cheekbone, and he throws you a look so pleading and helpless that it almost breaks through your resolve.

You glance around the car to make sure no one’s watching—you’re more visible from your aisle seat—then look back at Sans, and very deliberately run your hand down to the crotch of your pants. You start to rub yourself slowly through the rough material of your jeans, and you let a low, teasing moan escape you, quiet enough so that only he can hear.

“oh my god…” he groans, glancing frantically away, and then right back, gaze torn between your hand and your face, his eyes piercingly bright. You imagine him saying to hell with the rules and the other passengers, sliding his hand up your thigh, his fingers tangling with yours as he helps you touch yourself. You enjoy this image a great deal… and you like making him watch you enjoy it, eyes wild and hungry and fixated on your face.

“no fair,” he rasps, so quietly you can barely hear him.

With considerable mental effort, you pull your hand away from yourself and reach back into his shorts. He jolts in his seat when your fingers brush against the vibrator through the thick tape holding it in place.

“please, “ he whispers, “please, please, please please please,” over and over like a mantra.

The first time you tried to use a vibrator on him it rattled against the bone like a couple of rocks in the dryer. You both cackled like hyenas, mood completely ruined, and instead of fucking him with it you stayed up till 4am trading jokes about it and snickering under the covers.

But you got the hang of it eventually. It wouldn’t rattle if you pressed it against him tightly enough.

You find the remote where it’s taped to his femur and thumb the controls. You don’t turn it up any higher, but you switch it from a steady vibration to a pulsating rhythm. Sans gasps,  _ loudly_; the change in sensation is enough to put him immediately on edge, even if the vibration isn’t any stronger. You put your arm back around his shoulder and pull him tightly against you.

“Careful baby,” you murmur. “Don’t let anyone hear you.”

He chuckles weakly in response, but he’s only half-listening. His eyes are screwed shut, jaw tight, as he concentrates on the feeling. You still can’t hear the whir of the tiny motor unless you listen very carefully, but you can track the rhythm of it through his body language, on, off, on, off, feeling him shudder against you, his hand clenching and unclenching on your thigh.

“That feel any better?” you ask, and he just nods, no longer trusting himself to speak.

“If we were alone,” you whisper against his skull, “I’d put my hand down your shorts and stick my fingers through one of those holes at the front of your pelvis. Swirl them around along the inside edge real slow.”

His eyes meet yours in a silent plea.

“I’d make you feel so good,” you purr, leaning in closer. “Wrap my fingers around you and rub my thumb against that little gap in the center, where it’s really sensitive. Let you thrust against my hand.”

Sans raises a trembling hand to cover his mouth. It’s technically against the rules but you let him get away with it. He’s not looking at you anymore. He’s staring into space, clearly trying to imagine the feeling of your warm hands on him, rubbing and caressing, finally relieving the fevered ache that all your teasing has built up inside of him.

“Then,” you say, “I’d lay you down on your back—” He makes a low, needy sound, and you let some of your own breathless excitement creep into your voice. “—and run my tongue over you, get you all wet and hot for me. Then I’d wrap my lips around the bone, suckle on it… Get you so close…”

You can’t keep the needy whine out of your voice. You wish you really  _ were _ alone with him, and he’s clearly having similar thoughts; he looks so riled up and you’ve barely even touched him. His hand is still over his mouth, but through the gaps in his fingers you can see that his teeth are parted, ragged breaths coming quicker and quicker, expression screwed up and desperate. You’re not nearly as good at reading faces as he is, but you think you’ve been with him long enough to know what he looks like when he’s about to cum.

You wrap your arms around him at the same time that he reaches for you, grabbing fistfuls of your jacket and burying his face against your shoulder. The moans that he fights to suppress come out as hoarse mewls, muffled by the material of your jacket. You whisper to him unconsciously, “yes baby yes, yes,” stroking the back of his skull as he quakes in your arms and grinds his hips uselessly against the seat. Boy you hope no one’s watching this, there’s no way it doesn’t look like exactly what it is. As worked up as he was, his orgasm lasts a long time, and the threat of being discovered makes it feel longer still.

When his trembling begins to subside you reach down to the controls and turn off the vibrator. You could probably make him cum again, but you know he would only be louder the second time. You chance a glance around at the other passengers. You aren’t getting any scandalized glares, so you guess you got away with it…

Sans is slumped against you, wheezing a little as he tries to catch his breath. You stroke the bone just around the edges of the vibrator and he shudders from the gentle overstimulation. Bone-dry. Heh. The convenient thing about doing this to a skeleton is that there’s virtually no cleanup necessary. Can’t say the same thing for yourself, though. You resist the urge to rub yourself through your jeans again, certain that this time you won’t be able to stop. You don’t mind being on edge for a while. You’ll save it for when you get to the hotel.

“conductor comin’ for us?” Sans mumbles, with a little huff of laughter.

“No, you were quiet enough,” you whisper, and press a kiss to his cool forehead.


End file.
